COP9 signalosome complex subunit 2

COP9 signalosome complex subunit 2 (COPS2, also known as SGN2) is an essential component of the COP9 signalosome (CSN), a multi-subunit complex that regulates ubiquitin conjugation pathways and protein degradation (UniProt: P61201). The CSN complex mediates deneddylation of cullin subunits in SCF-type E3 ligase complexes, thereby modulating their catalytic activity. COPS2 additionally participates in phosphorylation of key regulatory proteins including p53, c-jun, and IκBα, and is involved in early-stage neuronal differentiation through interaction with NIF3L1.

The protein functions broadly in cellular and developmental processes related to protein quality control and signaling. No specific disease associations are documented in the UniProt record for COPS2.

In Alzheimer's disease, COPS2 is upregulated in post-mortem AD brain tissue compared to age-matched controls, with a mean log2 fold-change of 0.89 (Chaparral AD proteomics). This elevation was detected via TMT-labeled quantitative proteomics across multiple subcellular fractions, suggesting involvement of the ubiquitin-proteasome system in AD pathology.